My dogs can take my hand into their mouth with such a caution that there is not even play biting.. and they have learned all the hand signs etc. so they rock... sometimes when we go for a walk in the dark I have to look out because they go and catch a lonely walker thinking he/she can be dangerous but never do them harm. The queen of the house used to be my tini mini yorkie who was so brave when in my lap that she did bite the nose of the german sheps even when they came too close.
